Universal utility knife

Abstract

A utility knife especially suitable for use by either right-handed or left-handed persons includes a generally symmetrical casing, as viewed from the side, having a generally pointed leading edge and two surfaces sloping back at equal angles from the point. When a standard razor-like blade is positioned in the knife, the midpoint of the blade between its sharpened cutting edge and non-sharpened opposite edge, lies on an imaginary line extending from the point at the forward end of the casing and generally through the center of the knife. The blade may be positioned with its cutting edge being on one side or the other side of the imaginary centerline. In either position, the cutting edge of the blade will project similarly from the casing when a thumb piece is pushed toward the forward end.

What is claimed is: 
     
       1. A utility knife comprising: a casing assembly comprising two separable complementary halves secured together by a fastener for enclosing a removable slidable blade therein, said blade being slidable back and forth and having a cutting edge extending parallel to the direction of sliding, and a non-cutting edge opposite to said cutting edge, said casing assembly having an elongated slot at one end thereof, the length dimension between a first and a second end of second slot at least equaling the dimension of said blade between said cutting and non-cutting edges;   means for selectively aligning a blade with said slot, a portion of said blade and said cutting edge being subject to protruding from said slot when a blade is slid in one said direction toward said one slotted casing assembly end, said blade being selectively alignable with said cutting edge closer to one of said first slot end and said second slot end upon being removed from said casing assembly and reversed by being turned about an axis parallel to the cutting edge of the blade;   means, including a thumb piece, arranged externally on one side of said casing assembly for sliding said blade, said blade being in either selected blade alignment, said means for sliding responding to application thereto of an external force on said thumb piece; and means for automatically retracting a protruded blade and maintaining said blade within said casing assembly when said external force is released.   
     
     
       2. A utility knife as claimed in claim 1, wherein said casing as viewed from the side is generally symmetrical and has a pointed leading edge from the slotted end toward the rear of the casing. 
     
     
       3. A utility knife as claimed in claim 1, wherein said means for sliding said blade is arranged on one side of said casing and includes a thumb piece adapted to slide said blade upon application thereto of an external force from a thumb of a hand gripping said casing. 
     
     
       4. A utility knife comprising: a casing assembly comprising two separable complementary halves secured together by a fastener for enclosing a removable, slidable blade therein, said blade being slidable back and forth and having a cutting edge extending parallel to the directions of sliding, and an non-cutting edge opposite to said cutting edge, said casing assembly having an elongated slot at one end thereof, the length dimension between a first and a second end of said slot at least equaling the dimension of said blade between said cutting and non-cutting edges, said casing assembly as viewed from the side being generally symmetrical and having a pointed leading edge sloping from the slotted end toward the rear of the casing assembly;   means for selectively aligning a blade with said slot, a portion of said blade and said cutting edge being subject to protruding from said slot when a blade is slid in one said direction toward said one slotted casing assembly end, said blade being selectively alignable with said cutting edge closer to one of said first slot end and said second slot end upon being removed from said casing assembly and, reversed by being turned about an axis parallel to the cutting edge of the blade;   means, including a thumb piece, arranged externally on one side of said casing assembly, including a thumb piece for sliding said blade, said blade being in either selected blade alignment, said means for sliding responding to application thereto of an external force on said thumb piece; and means for automatically retracting a protruded blade and maintaining said blade within said casing assembly when said external force is released.